caa a22 4500 378912526 CHVBK 20180305123545.0 cr unu---uuuuu 161128e20041201xx s 000 0 eng 10.1524/zkri.219.12.773.55868 doi (NATIONALLICENCE)gruyter-10.1524/zkri.219.12.773.55868 Twins vs. modular crystal structures [Elektronische Daten] [Massimo Nespolo, Giovanni Ferraris, Slavomil Ďurovič, Yoshio Takéuchi] The crystallographic nature of modular structures is analysed and discussed in terms of their symmetry and structure building operations. The modular crystal structures we discuss in this paper are homogeneous edifices, built by one or more types of modules related by a point-space operation, and the whole structure is described by an ordinary three-dimensional triperiodic space group. Because the term "twin” is often used, with or without modifiers, to describe symmetry operations that act as building mechanisms in modular structures, a comparison is made with twins, that are instead heterogeneous edifices, described not by a space group but by a (polychromatic) point group, where the individuals are related by operations in the vector space. A unifying scheme is proposed where the passage from heterogeneous to homogeneous structures, only apparently justified by a change of dimensions of the individuals, implies a change of space where the operations are defined. © 2004 Oldenbourg Wissenschaftsverlag GmbH Crystallography nationallicence Inorganic chemistry nationallicence Organic chemistry nationallicence Nespolo Massimo aut Ferraris Giovanni aut Ďurovič Slavomil aut Takéuchi Yoshio aut Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 219/12(2004-12-01), 773-778 2194-4946 219:12<773 2004 219 zkri https://doi.org/10.1524/zkri.219.12.773.55868 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/zkri.219.12.773.55868 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nespolo Massimo aut NATIONALLICENCE 700 1- Ferraris Giovanni aut NATIONALLICENCE 700 1- Ďurovič Slavomil aut NATIONALLICENCE 700 1- Takéuchi Yoshio aut NATIONALLICENCE 773 0- Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 219/12(2004-12-01), 773-778 2194-4946 219:12<773 2004 219 zkri CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter